1. Field of the Invention
The present invention relates to a method of buffering image information suitable for use in a laser printer and the like, and more specifically, to a buffering method applicable to a case in which speed of reading-out the image information from a frame memory is slower than speed of writing the information onto a recording medium.
2. Description of the Related Art
An image information recording apparatus is widely in use, in which, for example, an image corresponding to the image information is recorded two-dimensionally onto a recording medium such as an unexposed film subjected to sub-scanning, by a laser beam modified by the image information and principally scanned by a rotating multiple surface mirror (a polygon mirror). In such an apparatus, multiple reflecting surfaces of the polygon mirror are used for scanning the laser beam. The laser beam is generated by a semiconductor laser, modified by the image information readout from a frame memory into which the image information has been stored, and sent to the polygon mirror.
In an image information recording apparatus such as the above, where the image information for each record line is written on the recording medium with the aid of each surface of the polygon mirror, the image information can be written realtime without a buffer memory if the reading-out speed is matched with the recording speed, provided that speed of reading-out the image information from the frame memory is greater than speed of writing the image information onto the recording medium based on the rotational speed of the polygon mirror.
However, when the writing speed is increased and it exceeds the reading-out speed, buffer memories become necessary to be provided between the frame memory and a writing unit. There has been conventionally a problem that the larger is the speed difference, the larger buffer memory becomes necessary.